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Battery test today.
- Thread starter superduperredz4
- Start date
Yes, I think all the E89's have IBS. But I can categorically tell you that as long as you change the battery for the same type (i.e AGM) and the same capacity then recoding is not critical.
Recoding is a bit of a misnomer really - resetting would be a better word. To be honest the primary motivation for this is money for the stealers...no doubt about it. As batteries age, their internal resistance rises slightly so ideally you need to increase the charging voltage slightly to get the same amount of current in. But mostly it's BS...on a massive scale.
Scaremongers out there will hence suggest that fitting a new battery to a car who's IBS thinks it still has the old one in will result in overcharging. In reality this is simply not true (and in any case it's very easy to measure the battery voltage before and after you fit the new battery with the engine running to check).
The IBS actively measures the following parameters:
In terms of recharge, what really matters are amps and hours - but the IBS monitors this. What damages a battery due to overcharging is primarily heat. But the IBS monitors this! This is a continuous live system.
Here's a good example: You take your original battery out of your car for a few hours to power some 12V items around your garage. Then you put it back in the car. The IBS now has a battery with a charge state which conflicts with it's data. Are you now saying that it must be recoded to work correctly? Of course not. It's all BS.
Same goes for a new battery that you are just about to fit. Is it 100% charged? 50% charged? Maybe it's been sat on a shelf for a year and is only 30% charged. The IBS doesn't know this - it has to work it out for itself through it's DYNAMIC measurements.
Fit a new battery of a similar type and capacity then just forget about it.
Recoding is a bit of a misnomer really - resetting would be a better word. To be honest the primary motivation for this is money for the stealers...no doubt about it. As batteries age, their internal resistance rises slightly so ideally you need to increase the charging voltage slightly to get the same amount of current in. But mostly it's BS...on a massive scale.
Scaremongers out there will hence suggest that fitting a new battery to a car who's IBS thinks it still has the old one in will result in overcharging. In reality this is simply not true (and in any case it's very easy to measure the battery voltage before and after you fit the new battery with the engine running to check).
The IBS actively measures the following parameters:
- Voltage (6V to 16.5V)
Current (-200A to +200A)
Standby Current (0A to 10A)
Starting Current (0A to 1000A)
Temperature (-40C to 105C)
Battery age (time since installation)
In terms of recharge, what really matters are amps and hours - but the IBS monitors this. What damages a battery due to overcharging is primarily heat. But the IBS monitors this! This is a continuous live system.
Here's a good example: You take your original battery out of your car for a few hours to power some 12V items around your garage. Then you put it back in the car. The IBS now has a battery with a charge state which conflicts with it's data. Are you now saying that it must be recoded to work correctly? Of course not. It's all BS.
Same goes for a new battery that you are just about to fit. Is it 100% charged? 50% charged? Maybe it's been sat on a shelf for a year and is only 30% charged. The IBS doesn't know this - it has to work it out for itself through it's DYNAMIC measurements.
Fit a new battery of a similar type and capacity then just forget about it.
Well for anybody sat on the fence you'd certainly have to make more of a case for registration. But let's look at battery charging characteristics here for a second:
All lead acid batteries were historically charged on a CV basis (constant voltage). That means you apply a voltage (typically 13.8V to 14.4V for boost charging) and you would see that charge current is quite high initially and then tails off exponentially as the battery approaches full charge. At full charge the current is minimal. On older cars it's as simple as that - the alternator puts out a steady voltage and the battery takes as much current as it needs to bring it back to a fully charged state. No intelligence required.
Modern manufacturers seem to have spotted a lucrative way to make this process more 'efficient' by keeping the alternator voltage lower (12.5V to 13.0V) when the battery does not need charging. In theory this reduces load on the engine and results in better mpg, emissions..blah blah blah. In truth it's just more BS. In a conventional system, as stated earlier, the battery current when fully charged is very small anyway, so even with the alternator pumping out 14.4V, the extra energy used is tiny.
So...let's talk about charging profiles for different capacity batteries. The only argument I can foresee for BMW having this information stored in the IBS is that they can see how many amp hours have been taken out so that only the required amount of amp hours has to be put back in. Unfortunately the principle is highly floored because batteries don't recharge 100% efficiently, i.e. you have to put more back in than you take out. Furthermore the amount of extra amp hours that you have to put back in is highly variable depending on battery manufacturer / batch / tolerances. It would be crazy to manage battery charging on that principle alone.
THE ONLY RELIABLE WAY YOU CAN TELL IF A BATTERY IS FULLY CHARGED IS TO LOOK FOR THE DROP OFF IN CHARGE CURRENT AT A CONSTANT VOLTAGE.
This being the case, I really can't see the capacity being that relevant. I guess we still don't know the full intricacies of the IBS system but we do know how lead acid batteries charge and common sense must prevail at some point here!
All lead acid batteries were historically charged on a CV basis (constant voltage). That means you apply a voltage (typically 13.8V to 14.4V for boost charging) and you would see that charge current is quite high initially and then tails off exponentially as the battery approaches full charge. At full charge the current is minimal. On older cars it's as simple as that - the alternator puts out a steady voltage and the battery takes as much current as it needs to bring it back to a fully charged state. No intelligence required.
Modern manufacturers seem to have spotted a lucrative way to make this process more 'efficient' by keeping the alternator voltage lower (12.5V to 13.0V) when the battery does not need charging. In theory this reduces load on the engine and results in better mpg, emissions..blah blah blah. In truth it's just more BS. In a conventional system, as stated earlier, the battery current when fully charged is very small anyway, so even with the alternator pumping out 14.4V, the extra energy used is tiny.
So...let's talk about charging profiles for different capacity batteries. The only argument I can foresee for BMW having this information stored in the IBS is that they can see how many amp hours have been taken out so that only the required amount of amp hours has to be put back in. Unfortunately the principle is highly floored because batteries don't recharge 100% efficiently, i.e. you have to put more back in than you take out. Furthermore the amount of extra amp hours that you have to put back in is highly variable depending on battery manufacturer / batch / tolerances. It would be crazy to manage battery charging on that principle alone.
THE ONLY RELIABLE WAY YOU CAN TELL IF A BATTERY IS FULLY CHARGED IS TO LOOK FOR THE DROP OFF IN CHARGE CURRENT AT A CONSTANT VOLTAGE.
This being the case, I really can't see the capacity being that relevant. I guess we still don't know the full intricacies of the IBS system but we do know how lead acid batteries charge and common sense must prevail at some point here!